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can be due to hormonal problem;ovarian cyst;anaemia;thyroid problems;stress and in your case may be it was polycystic ovarian syndrome
.The periods will become regular but after taking the follicular study
i guess you did not complete and even you did not consult your doctor.Please understand that to get pregnant these things are important like:-
-proper follicle formation and rupture of it to release ovum
-patent fallopian tubes
-normal semen analysis
of your husband.
So complete the follicular study and consult your doctor to make periods regular and induction of ovulation.